/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Reflection;
using Spring.Core;
using Spring.Util;

namespace Spring.Objects.Events.Support;

/// <summary>
/// Utility class to aid in the manipulation of events and delegates.
/// </summary>
/// <author>Griffin Caprio</author>
public sealed class EventManipulationUtils
{
    /// <summary>
    /// Returns a new instance of the requested <see cref="Delegate"/>.
    /// </summary>
    /// <remarks>
    /// <p>
    /// Often used to wire subscribers to event publishers.
    /// </p>
    /// </remarks>
    /// <param name="delegateType">
    /// The <see cref="System.Type"/> of delegate to create.
    /// </param>
    /// <param name="targetSubscriber">
    /// The target subscriber object that contains the delegate implementation.
    /// </param>
    /// <param name="targetSubscriberDelegateMethod">
    /// <see cref="MethodInfo"/> referencing the delegate method on the subscriber.
    /// </param>
    /// <returns>
    /// A delegate handler that can be added to an events list of handlers, or called directly.
    /// </returns>
    public static Delegate GetHandlerDelegate(
        Type delegateType, object targetSubscriber, MethodInfo targetSubscriberDelegateMethod)
    {
        return Delegate.CreateDelegate(
            delegateType, targetSubscriber, targetSubscriberDelegateMethod.Name);
    }

    /// <summary>
    /// Queries the input type for a <see cref="MethodInfo" /> signature matching the input
    /// <see cref="MethodInfo"/> signature.
    /// </summary>
    /// <remarks>
    /// Typically used to query a potential subscriber to see if they implement an event handler.
    /// </remarks>
    /// <param name="invoke"><see cref="MethodInfo"/> to match against</param>
    /// <param name="subscriberType"><see cref="Type"/> to query</param>
    /// <returns>
    /// <see cref="MethodInfo"/> matching input <see cref="MethodInfo"/>
    /// signature, or <see langword="null"/> if there is no match.
    /// </returns>
    public static MethodInfo GetMethodInfoMatchingSignature(
        MethodInfo invoke, Type subscriberType)
    {
        ParameterInfo[] parameters = invoke.GetParameters();

        ComposedCriteria criteria = new ComposedCriteria();
        criteria.Add(new MethodReturnTypeCriteria(invoke.ReturnType));
        criteria.Add(new MethodParametersCountCriteria(parameters.Length));
        criteria.Add(new MethodParametersCriteria(ReflectionUtils.GetParameterTypes(parameters)));

        MemberInfo[] methods = subscriberType.FindMembers(
            MemberTypes.Method, ReflectionUtils.AllMembersCaseInsensitiveFlags,
            new MemberFilter(new CriteriaMemberFilter().FilterMemberByCriteria),
            criteria);
        if (methods != null
            && methods.Length > 0)
        {
            return methods[0] as MethodInfo;
        }

        return null;
    }

    /// <summary>
    /// Creates a new instance of the EventManipulationUtilities class.
    /// </summary>
    /// <remarks>
    /// <p>
    /// This is a utility class, and as such has no publicly visible constructors.
    /// </p>
    /// </remarks>
    private EventManipulationUtils()
    {
    }

    // CLOVER:ON
}
